Molecular and carbon and hydrogen isotopic composition of n-alkanes in plant leaf waxes

Molecular composition and compound-specific carbon and hydrogen stable isotope ratios of leaf wax n-alkanes are presented for 26 plant species operating C3, C4 and CAM photosynthetic pathways. In contrast to δ13C values, δD values are not diagnostic discriminators for C3, C4 and CAM plants. δD and δ13C values of n-alkanes from C4 plants seem to express an inverse linear relationship while some C3 plants showed a positive relationship. The carbon and hydrocarbon isotopic correlation is dependent on plant types as well as photosynthetic pathways. However, our data imply that the combined use of carbon and hydrogen isotopic characterization may have superior diagnostic potential for source apportionment when compared with more limited isotopic approaches.